Vending Machine Simulator

A fully-functional C++14 vending machine for a fictional pastry company, focused on robust programming, clean code, and dynamic memory management. Operates entirely in a console environment with persistent file-backed storage.

• Product display, purchases, stock management, coin handling, and admin operations
• Strict input and file validation with meaningful error messages
• Custom singly & doubly linked lists built from scratch (no STL containers)
• Manual new/delete verified leak-free with Valgrind

• Abstract LinkedList base class with virtual printLL, findItem, saveLL, resetStock, remove, addLL, and deleteLL
• LinkedListSingle — singly-linked list for inventory traversal
• LinkedListDouble — doubly-linked list with prev/next pointers enabling reverse display
• Node / NodeD classes encapsulating product data (ID, name, description, price, on-hand quantity)
• Strategy-style runtime switching between the two list implementations

• VendingMachine — core orchestrator managing state and command dispatch
• Command Pattern — eight command classes (Abort, DisplayItem, PurchaseItem, Save, AddItem, RemoveItem, DisplayCoins, ResetCoins)
• Menu — UI layer for command selection
• Coin / Price — currency representation and change calculation
• Helper — static validation utilities for stock/coin formats and input parsing

• 16+ test suites covering all major features and edge cases
• Functional & purchase tests — exact change, insufficient funds, out-of-stock, invalid selection
• Admin tests — coin reset, restock, forward/reverse display, add/remove items
• Edge cases — malformed files, invalid delimiters, negative values, empty input
• Memory safety — zero leaks across all operations, verified by Valgrind